It would often be extremely useful to quickly, accurately and inexpensively monitor energetic alpha particles found in ambient air. Monitoring airborne energetic alpha particles would be extremely useful because air containing alpha particles is considered to be unhealthy and a possible cause of lung cancer. While making such measurements is highly desirable and very useful, those skilled in the art realize that this is a difficult task to accomplish because of the properties of oxygen in air. Air contains oxygen, which is an electron positive gas that allows oxygen ions to quickly attract electrons to become negative ions.
Public health officials, the Environmental Protection Agency and related federal and state agencies believe that adverse health effects, including lung cancer, can be induced from the inhaling air containing contamination-emitting alpha particles. Based on this widespread belief, a direct measurement of alpha activity in the ambient air is the best approach of assessing the threat to the general public. Up until now, the general approach for assessing this serious health risk has been to measure the Radon content in air instead of the number of alpha particles in units of disintegrations per minute per liter (dpm−1) of air. Measuring alpha particles in dpm 1−1 of air is a much more important and meaningful parameter because the potential energy deposited in lung tissue can be determined from this measurement. The current commercial radon measurement technique is to collect radon in a charcoal filter that is sent to a laboratory where the gamma ray emission is counted and correlated with the equivalent number of picoCuries per liter (pCi l−1) of alpha particles in ambient air. Another procedure is to use a gamma ray counter to measure radon activity directly at the site. Such commercial procedures require placing a charcoal canister within a home or commercial building for a week, then sending the sample to a laboratory for testing and waiting for the test results. This technique suffers from a number of serious drawbacks and is considered inadequate. One significant disadvantage with this approach is that radon concentration is only proportional to potentially harmful alpha emitters in those cases where secular equilibrium of radon with its daughter products exists, or is at least a fixed fraction. In practice, this is never the case, because this equilibrium varies between 10% and 90% depending on location and time. Directly measuring the radon activity on site is a better approach but it still has the same disadvantage. Other shortcomings with the current radon concentration approach are that other natural sources of alpha particle activity such as Thorium and Uranium are not included in the radon measurements and none of the commercial measurements procedures are made in real time.
Thus there has been a long-felt need for a timely, accurate and inexpensive way to monitor energetic alpha particles found in ambient air. This invention provides a device to directly measure the alpha activity in ambient air with an open air ionization chamber that counts alpha pulses, and will fulfill the long-felt need for a timely, accurate and inexpensive way to monitor energetic alpha particles found in ambient air and improve the assessment of the serious public health risk, without suffering from any of the disadvantages, shortcomings and limitations of prior art devices.